Achievements so far

The understanding of tinnitus has advanced considerably in the past decade, and several important pieces to the puzzle of how tinnitus arises have been found recently in BTA-funded research at the UCL Ear Institute.

The most important trigger for tinnitus is damage to the inner ear, which usually manifests itself as hearing loss. However, we now know that the tinnitus itself is generated in the brain, not in the ears. Tinnitus is generated because the information processing in the brain is pathologically altered, creating the illusion of sound out of silence.

An important part of the process is that nerve cells in the brain become hyper-excitable after hearing loss. They then start to amplify neuronal noise and generate the phantom sound. The key to finding a cure for tinnitus is thus firstly to understand why these processes take place, and secondly to find ways of specifically reverting the pathological changes. So far, there is no real cure for tinnitus, just management strategies that can reduce the suffering.

BTA-funded research at the UCL Ear Institute has recently shown that even tinnitus patients with apparently normal hearing do in fact have ‘hidden hearing loss’, manifesting itself as a reduced signal in the auditory nerve even though the hearing thresholds are normal. Interestingly, the brain compensates for this reduced input already at the first processing stages of the auditory pathway. Tinnitus-related changes in the brain thus take place already at a sub-cortical level.

Furthermore, Dr Roland Schaette (pictured right) and colleagues have also been able to demonstrate that the illusion of sound can also be induced when hearing loss is simulated for several days with an earplug. These findings can be explained by a computer model of tinnitus development, which shows that an attempt of the brain to compensate for hearing loss can explain hyper-excitability and tinnitus.

In the current project, researchers at the Ear Institute will set out to tease apart the details of the mechanisms that give rise to tinnitus. The plan is to investigate how tinnitus changes information processing in the auditory brain, to test different ways of influencing the response properties of the nerve cells involved in the generation of tinnitus, and to develop and test pharmaceuticals that have the potential to reverse the pathological changes, with the ultimate goal of developing a pill for tinnitus.